Uses for Acetazolamide

Glaucoma

Short-term use in acute angle-closure glaucoma to lower intraocular pressure (IOP) before surgery.abcde Should not be used for long-term treatment of angle-closure glaucoma.bcde (See Contraindications under Cautions.)

Acute Mountain Sickness

Shortens the time of acclimatization.f If acute mountain sickness develops, shortens duration; does notobviate need to stop ascent or to descend.f

Also used in the treatment and prevention of high-altitude sleep disorders.cdf Decreases periodic breathing and apnea and improves oxygenation.f

Seizure Disorders

Management (in combination with other anticonvulsants) of centrencephalic epilepsies (e.g., petit mal, unlocalized seizures);ce may be ineffective for prolonged therapy.ab Has not been evaluated in controlled clinical studies in specific seizure types.ab

Edema

Adjunctive treatment of edema due to CHF or drug therapy.bce Less potent diuretic than thiazide diuretics; metabolic acidosis resulting in loss of diuretic effect occurs after 2–4 days of continuous therapy.b

Periodic Paralysis

Has been used in the treatment of hyperkalemic and hypokalemic forms of periodic paralysis†.404405407409412413

Acetazolamide Dosage and Administration

Administration

Oral Administration

When an oral liquid preparation is needed, crush the appropriate number of tablets and suspend in a highly flavored carbohydrate syrup.a Can suspend up to 500 mg of acetazolamide in 5 mL of syrup; suspensions containing 250 mg per 5 mL are more palatable.a Alternatively, soften a tablet in 2 teaspoonsful of hot water and add 2 teaspoonsful of honey or syrup; swallow immediately.a

When the extended-release capsules are used for glaucoma, if adequate response is not achieved with twice-daily administration of this preparation, consider using other acetazolamide preparations that are administered more frequently (i.e., tablet, parenteral preparation) to achieve IOP control.d

IV Administration

For solution and drug compatibility information, see Compatibility under Stability.

Administer IV when rapid lowering of IOP is necessary or if patient is unable to take oral medication.ae

Reconstitution

Reconstitute vial containing 500 mg of acetazolamide with 5 mL of sterile water for injection to provide a solution containing 100 mg/mL.ae

Dosage

Available as acetazolamide (oral preparations) and acetazolamide sodium; dosage expressed in terms of acetazolamide.cde

Acute Angle-closure Glaucoma

Acute Mountain Sickness

Oral

Children ≥12 years of age: 500 mg once or twice daily as extended-release capsules.d Initiate 24–48 hours before ascent; continue for 48 hours while at high altitude or longer if needed to control symptoms.d

Acute Mountain Sickness

Oral

Conventional tablets and extended-release capsules: 500 mg to 1 g daily in divided doses.cd Initiate 24–48 hours before ascent; continue for 48 hours while at high altitude or longer if needed to control symptoms.cd

125–250 mg twice daily starting 24 hours before ascent has been effective for prevention of acute mountain sickness; 500 mg (as extended-release capsules) every 24 hours also has been effective.f 750 mg daily may be more effective than 500 mg daily.f

125 mg at bedtime has been used for the management of high-altitude sleep disorders.f

For treatment of acute mountain sickness, some experts recommend 250 mg given within 24 hours of onset of symptoms and a second 250-mg dose 8 hours later.f

Edema

CHF

If patient fails to lose edema fluid after initial response, hold drug for 1 day. c To avoid loss of diuretic effect, administer intermittently (on alternate days or for 2 days followed by a drug-free day).c

If patient fails to lose edema fluid after initial response, hold drug for 1 day.e To avoid loss of diuretic effect, administer intermittently (on alternate days or for 2 days followed by a drug-free day).e

Drug-induced Edema

Oral

Conventional tablets: 250–375 mg once daily for 1 or 2 days, alternating with a drug-free day.c

IV

250–375 mg once daily for 1 or 2 days, alternating with a drug-free day.e

General Precautions

CNS Effects

Respiratory Effects

Caution in patients with pulmonary obstruction, emphysema, or advanced pulmonary disease where alveolar ventilation may be impaired.bcde Acetazolamide may precipitate or aggravate acidosis in these patients.cde

Laboratory Monitoring

Monitor for hematologic reactions associated with sulfonamides; obtain a CBC and platelet count before therapy and periodically during therapy.cde Discontinue the drug if clinically important changes occur.cde

When used as a diuretic, plasma bicarbonate concentration is decreased and chloride concentration may be increased, resulting in metabolic acidosis.b In the presence of acidosis, diuretic effect ceases.b

In acute mountain sickness, the effect of acetazolamide on acid-base balance (i.e., increased renal excretion of bicarbonate that leads to metabolic acidosis) results in compensatory hyperventilation and improved oxygenation.f

Exact mechanism of anticonvulsant activity unclear; may be due to metabolic acidosis, inhibition of carbonic anhydrase in the CNS, or other mechanisms.b

Advice to Patients

When used to prevent acute mountain sickness, importance of gradual ascent.cf Use of acetazolamide does notobviate need to stop ascent if acute mountain sickness develops or descend if severe forms of altitude sickness (e.g., high attitude pulmonary or cerebral edema) occur.cf

Potential for the drug to impair mental alertness or impair vision (myopia); use caution when driving a vehicle or operating machinery until effects on individual are known.d

Advise patients with pulmonary obstruction or emphysema that the drug may precipitate or aggravate acidosis.cd

Advise patients with diabetes or impaired glucose tolerance that increases and decreases in blood glucose have occurred in acetazolamide-treated patients.d

Importance of informing clinicians of existing or contemplated concomitant therapy, including prescription and OTC drugs (e.g., high-dose aspirin), as well as concomitant diseases.cde

Importance of women informing clinicians if they are or plan to become pregnant or plan to breast-feed.cde

Importance of informing patients of other precautionary information.cde (See Cautions.)

Preparations

Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.